Manufacture of steel from phosphoritic iron.



UNITED STATES PATENT OFFICE.

JACOB REESE, OF SHARON HILL, PENNSYLVANIA, ASSIGNOR TO THE STEEL PATENTSCOMPANY, A CORPORATION OF PENNSYLVANIA.

h'iiihlUi-ACTURE OF STEEL FROM PHUSPi-IORlTlC IRON.

Specification of Letters Patent.

Patented May 29. 1906.

Application filed September 23,1905. Serial No. 279,887.

To 0,55 whom it may concern:

Be it known that I, Jiicon REEsE, of Sharon Hill, county of Delaware,and State of Pennsylvania, have invented a new and useful Improvement inthe Manufacture of Steel from Phosphoritic Iron; and I do hereby dcclarethe following to be a full, clear, and 020 act description thereof.

This invention relates to a process of manufacturing iron or steel fromphosphoretic iron ore, and has for its object to so treat the metal forthe purpose of dephosphorization that the cost of the iron or steel ismaterially reduced throu all the production as a by-prodnot of ahighly-phosphoretic slag of great commercial value.

To this end my present invention may be, generally stated, as, ineffect, a modification of the process set forth in Letters Patent forthe manufacture of iron and steel, numbered 401.903, granted to me April23, 1889, Whereby the same is adapted es ecially to the sec nomictreatment of iron ow in hosphorus, said modification, broadly statedconsisting in the substitution for the basic bathof oxid of calcium freefrom or low in phosphorus of a calcium-phosphate bath Whose percentageof phosphoric acid when added to that derived from the molten metalshall augment the phosphoric acid in the resultant slag to at leastfifteen and not to exceed twenty-two per cent.

The process embodied in my former patent hereinbefore referred to maybebriefly stated as one wherein the phosphoretic iron is first vpractically dcsiliconized and decarburized in a Bessemer convcrterfthcntransferred to an open hearth wherein in the presence of a bath oi themetallic oxide, which may include the oxid of calcium, the fluidity andheat of themctal is maintained by fuel extraneous thereto until all, orsubstantially all, of the phosphorus and residual impurities, such assilicon, have passed from the metal into the slag. In practice thisprocess has proven "very economical in the treatment of iron ores highin phosphorus by reason of the production of a by-product-to Wit, a slaghigh in soluble phosphates and valuable as a fertilizer, but of lessvalue in the case of ores low in phosphorus, as in the lattercase theresultant is deficient in phosphorus In order that the resultant slagshall be of practicai value a fertilizer, it should contain at leastfifteen percent. of be low in silicates.

In the practice of the basic process for dephosphorization of ironexperience has shown that the basic additions will take up as high astwenty-two (22) per cent. of phosphoric acid if the same be present inthe molten metal, and it is of this property of the basic bath that Iavail myself in the treatment of iron low in phosphorus by my presentprocess, which will now be described. Having first ascertained the percent. of phosphoric acid present in the metal to be operated upon, Idraw the molten metal from the blast-furnacc or the cupola, as the casemay be,into a Bessemer or similar converter, subjectin the same thereinto the usual air-blast until the contained carbon and silicon have beenreduced by oxidation to the desired minimum. After the removal of theslag the molten metal from the converter is transferred to apreviously-heated basic-lined open-hearth furnace and therein treated toa basic bath of lime and mineral phosphates which are as free fromsilica as it is possible to obtain and containin 'such a ercentage ofhosphoric acid as w en adde to the phos ,lorus present in the iron shallproduce a slag containing not more than twenty-two (22) per cent. norless than fifteen (15) per cent. of phosphoric acid. The fluidity of themolten metal in the open hearth is maintained in the usual manner untilsuch time as the molten metal has been freed of its impurities and thephosphates have been taken up by the-slag, after which rccarburizationto the desired extent may be effected b the addition to the molten metalof spiegcreiscn or ferromanganose as required by the character of steelto phosphoric acid and be produced. i

Having thus described my invention, What I claim, and desire to secureby Letters Patent, is-- 1. The process herein described in themanufacture of steel from phosphoritic iron, which consists indesiliconizing and decarbonizing the metal, in a Bessemer converter,then conveying it into' a basic-lined open hearth and therein at a hightemperature subjecting it to the action of basic additions containingphosphate of lime, until the phosphorus is removed from the metal and isheld in the slag as a phosphate, substantially as and for the purposeset forth.

2. In the manufacture of steel from phosphoritic iron, the method ofdephosphorizing the metal by the use of basic additions containingphosphates, which consists in desiliconizing molten iron, then placingit in a basic-lined open hearth, then subjecting it to a hightemperature while treated with basic additions containing phosphate oflime, until the metal has been purified, and the slag formed by thebasic additions contains at' least fifteen per cent. of phosphoric acid.

3. The process herein described for the manufacture of iron and steeland the production of a slag high in phosphoric acid from iron low inphosphorus, consisting in first desiliconizing and decarburizing themolten metal in a Bessemer converter, then transferring the molten metalfrom the-con.-

verter to a basic-lined open-hearth furnace and subjecting the moltenmetal therein to a basic bath having a percentage of phosphoric acidwhich when added to the phosphorus of the metal shall produce a slaghaving not less than fifteen (15) per cent. nor more than twenty-two(22) per cent. of phosphoric acid, the temperature and fluidityof thebath being maintained during said additions to the molten metal.

In testimony whereof I affix my signature in presence of two Witnesses.JACOB REESE.

Witnesses: JAMES MGGAHEY, WM. P. PAINTER.

